1. Field of the Invention
The present invention relates to a method of manufacturing a glass substrate in which a plurality of through electrodes is formed in the glass substrate and a method of manufacturing an electronic component using the method.
2. Background Art
Recently, piezoelectric vibrators using quartz crystal or the like have been used in time sources or timing sources of cellular phones or mobile information terminal devices. There are many types of piezoelectric vibrator, and, as one of them, a piezoelectric vibrator of a surface mounting type is known. As such a piezoelectric vibrator, a three-layer structure type is known in which a piezoelectric substrate, in which a piezoelectric vibrating piece is formed, is vertically interposed and bonded between a base substrate and a lid substrate. The piezoelectric vibrating piece is housed inside a cavity that is formed between the base substrate and the lid substrate.
In addition, recently, piezoelectric vibrators of a two-layer structure type have been developed. This type is configured by a package of a two-layer structure type in which a base substrate and a lid substrate are directly bonded to each other, and a piezoelectric vibrating piece is housed inside a cavity that is configured between the base substrate and the lid substrate. A piezoelectric device of the two-layer structure type has advantages over a piezoelectric device of the three-layer structure type in that the thickness thereof can be formed thin and the like.
In JP-A-2002-124845 and JP-A-2002-121037, quartz crystal vibrator packages of the two-layer structure type are disclosed. As the package material of the base substrate and the lid substrate, glass is used. Since glass is used, molding can be performed in a relatively easy manner, and the manufacturing cost can be lower than that of a case where ceramics are used. In addition, since glass has a low thermal conductivity coefficient, the thermal insulating properties thereof are superior, whereby a piezoelectric vibrator disposed therein can be protected from changes in temperature.
In JP-A-2003-209198, a method of simultaneously forming a plurality of quartz crystal vibrator packages of the two-layer structure type as described above is disclosed. In this case, a method is disclosed in which glass is used as the material of a base substrate, and through electrodes formed from a metal material are formed in the base substrate. When the through electrodes are formed in the glass, first, through holes are formed in a glass plate. FIGS. 11A and 11B illustrate a method of forming through electrodes formed of metal pins 115 in the glass plate 131 (FIG. 3 in JP-A-2003-209198). FIG. 11A illustrates a method of forming through holes 119 in the glass plate 131. The glass plate 131 is arranged at the bottom of a die 126. In the die 126, a heater 125 is installed and can apply heat to the glass plate 131. On the upper side of the die 126, a punching machine configured by a puncher 129 is installed. On the side of the puncher 129 that is the glass plate 131 side, drilling pins 128 are installed, and a heater 127 is installed in the puncher 129 as well. After the glass plate 131 is heated at a predetermined temperature, the puncher 129 is lowered so as to form the through holes 119.
FIG. 11B illustrates a method of driving metal pins 115 into the through holes 119 of the glass plate 131. The glass plate 131 in which the through holes 119 are formed is installed to a base 135, and glass frit 132 is blown to the through holes 119 by a glass frit blower 133, and the metal pins 115 are driven into the through holes 119 by a metal pin puncher 134.
FIGS. 12A and 12B illustrate a press molding process (FIG. 4 of JP-A-2003-209198). As illustrated in FIG. 12A, the glass plate 131 in which the metal pins 115 are driven into the through holes 119 is installed between a pressing lower die 136 and a pressing upper die 137. In the pressing upper die 137, a partition convex ridge 138, a pinhead housing concave portion 139, and a concave-portion forming convex ridge 141 are formed. This die is input into an electric furnace and is heated at a temperature equal to or higher than 1000° C. while pressing the pressing upper die 137 to the pressing lower die 136. As a result, as illustrated in FIG. 12B, the concavity and convexity of the surface of the pressing upper die 137 is transferred onto the glass plate 131, and a division groove 142 and concave portions 116 are formed in the glass plate 131. Simultaneously, through electrodes that are configured by the metal pins 115 having sealability are formed in the glass plate 131.